The vitreous body is a connective tissue with an organized structure. More than anything else, the investigation to date has emphasized the complexity of the connective tissue and spotlighted possible approaches to understanding its structure and function. Hyaluronic acid and collagen are two major components of the vitreous. The knowledge of the relationship between these two macromolecules is fundamental to an understanding of the organization of the vitreous. Any interrelationship between these polymers can only be studied when the structural details of the individual components are well known. This project proposes to use viscosity, sedimentation, and spectroscopic technique, such as circular dichroism, optical rotation, infrared, etc., to study the structural properties of hyaluronic acid and its interaction with collagen and other proteins of the vitreous. Since the vitreous body shows a gel-liquid transition in the aging processes, studies of this conformational transition or the interaction properties of different components of the vitreous will be monitored by optical methods and by a Differential scanning calorimeter. The clinical application of hyaluronic acid as a vitreous substitute underlines the urgency of intensified fundamental research on the molecular structure of this biopolymer.